The present invention relates to a device for degassing liquids and slurry materials and more particularly to a device using a centrifugal force field for degassing drilling mud.
In the case of oil field drilling mud, the mud often comes in contact with gasses in the well which become dissolved due to the high operating pressures involved. As the mud rises toward the surface, the pressure is reduced and the gasses will evolve, i.e., become entrained in the mud. This will result in a reduction of the column "mud" weight. Upon reaching the surface the gasses must be removed before the mud reaches a mud pump for further recycling. If the gasses are not removed pump performance is jeopardized. If the gasses are allowed to remain in the used mud, upon recycling there is accelerated infusion of gas leading to blowout conditions. Finally, gassed muds tend to "bind" or "vapor lock" centrifugal pumps in use on the oil rigs.
There are presently several methods for degassing drilling mud. One method includes the spreading of the mud into thin layers or small droplets in the presence of a vacuum to accelerate bubble rise out of the mud. A second method includes impacting the mud droplets to help burst the bubbles in the presence of a vacuum for a combined effect. And a third method includes using high shear rates and impacting alone to release the bubbles.
Using any of these methods requires the movement of mud to and from the degasser. This may be accomplished by any one of the following methods:
(a) a mud jet eductor creates a vacuum that moves the mud into and out of the degasser; PA1 (b) a vacuum pump creates a vacuum that moves the mud into the degasser and a centrifugal pump moves the mud out of the degasser; and PA1 (c) a low head centrifugal pump moves the mud into and out of the degasser.
These methods have the following major problems respectively:
(a) a large horsepower motor or engine driven pump is required to operate the mud jet eductor and a large space is required for the degasser;
(b) the centrifugal pump that is used to move the mud out of the degasser often vapor locks and a large space is required for the degasser; and,
(c) the degasser using a low head centrifugal pump to move the mud does not degas effectively.